Well, as long as we're strolling down Peter Marshall memory lane ...
I remember seeing him in a syndicated rerun of "The Millionaire." I don't remember what his character did, but he was married to a predictably pretty wife, and they have financial problems. They have a predictably spunky young son who's the recipient of John Beresford Tipton's largesse. So when the kid proudly shows his parents his savings passbook (do they give those out anymore?), they're shocked to see the amount of $1,000,000. Worse, it's a passbook where customers write in the amounts themselves (really?), so they assume the kid made up the $1,000,000 deposit. After a fair amount of screaming and yelling and calming down, the parents decide the kid's heart was in the right place, and IIRC, the episode ends with Peter Marshall and wife telling the kid they'll go to the bank tomorrow and straighten things out, and the kid smiles because he knows that when they do, his parents will know the money's for real. Happy ending.
The other Marshall acting appearance I recall is a segment on "Love, American Style" in which he played the producer of some amateur variety TV show. He's on his honeymoon with his predictably gorgeous wife, and they're constantly being interrupted by would-be auditioners who keep crashing their hotel suite on various pretexts. The ending was something of a shocker.